Chain lock indicator



Feb. 3, 1970 D. A. RAMLER CHAIN LOCK INDICATOR Filed Jime' 12. 1968 INVEN TQR ATTORNE; 8

DAVID A. RAMLER W FIG. 5

United States Patent 3,493,256 CHAIN LOCK INDICATOR David A. Ramler, 155 Shaw Road, Chestnut Hill, Mass. 02167 Filed June 12, 1968, Ser. No. 736,342 Int. 'Cl. E05c 13/10, 17/36; E05b 41/00 U.S. Cl. 292264 5 Claims ABSTRACT OF THE DISCLOSURE A chain lock indicator for visually denoting the locked status of a door. The lock includes a keeper plate mounted on a door and a link chain assembly mounted on an adjacent door jamb with a fastening member adapted for retention by the keeper plate. An indicator rod is slidably mounted in an opening through the door and a cam and spring assembly within the keeper plate is operative, in the absence of the fastening member in the keeper plate, to maintain the indicator rod in a retracted position, and operative, in the presence of the fastening member in the keeper plate, to force the rod beyond the outside surface of the door thereby to indicate the locked condition thereof.

FIELD OF THE INVENTION This invention relates generally to indicator locks and more particularly to chain lock indicator mechanisms.

BACKGROUND OF THE INVENTION Various indicator mechanisms are known for use in locks employed, for example, in hotel room doors, which denote the locked or unlocked status of a door. Conventional indicator mechanisms generally employ an arrangement of mechanical linkages which are operative upon the turning of a handle or upon operation of a lock bolt to move an indicator into position for visual indication of the engagement of the lock. Such mechanisms are often quite complex and must be designed and fabricated as an integral part of the lock itself to provide a proper working device. In many instances, it would be desirable to provide a means of indicating the locked condition of a door without the necessity for a specially made indicator lock to provide the visual indication. It is, therefore, an object of the present invention to provide an extremely simple and effective indicator mehcanism which can be installed in a door without any modification of a conventional door lock.

SUMMARY OF THE INVENTION In accordance with the present invention, a simple and effective indicator mechanism is employed with a chain lock assembly to provide a visual indication of the locked door condition when the chain lock is fastened. The chain lock includes a keeper plate having an elongated channel formed therein which confronts the door surface on which the plate is mounted, and an elongated slot formed in a front surface of the keeper plate and colinear of the channel, one end of the slot having an enlarged opening formed therein. This keeper plate is adapted for mounting by suitable fasteners onto a door adjacent the openable end thereof and with the enlarged slot opening being disposed further from this end. A link chain is provided with one end being attached to a mounting plate adapted for attachment to a door jamb or other surface adjacent the movable door, and the other end being attached to a fastener member which is operative to be inserted within the enlarged opening in the keeper plate and to he slidable within and retained by the keeper plate slot. With the fastener member retained within the keeper plate, the door is capable of being opened to a slight degree 3,493,256 Patented Feb. 3, 1970 beyond which movement is prevented by the chain extending between the keeper plate and the mounting plate. To chain lock, as thus far explained, operates in a wellknown manner to provide a safety lock which allows the door to be partially opened to ascertain the identity of a caller and yet does not allow the door to he opened sufficiently to allow entrance into a room. Such entrance can only be gained by closing the door and removing the chain from the keeper plate.

According to the principles of this invention, a novel indicator mechanism is employed with the chain lock to provide visual indication of the locked condition of the door when the chain is in place. Thus, for example, in hotel rooms, a maid going about her duties, 'will immediately know that a room cannot be entered if the indicator is visible. The novel indicator mechanism includes an indicator rod having a length somewhat greater than the thickness of a door with which it is employed and adapted for slidable passage through an opening in the door so that the rod can be selectively moved to a position extending outwardly from the outside surface of the door and to a retracted position substantially flush with or recessed within the door. The end of the indicator rod inward of the door confronts and is extendable into a region of the keeper plate channel away from the enlarged opening formed therein. This end of the indicator rod is operatively associated with a spring mechanism which is disposed within the channel of the keeper plate, the spring mechanism being operative to urge the indicator rod into its recessed or inwardmost position in the absence of the chain fastening member being retained within the keeper plate. The spring mechanism is also operative when the chain fastening member is inserted into the keeper plate slot to urge the indicator rod into its protruded position outwardly of the outside surface of the door. Thus, the placement of the chain in the keeper plate causes operation of the indicator rod so that the locked status of the door is visible from the outside.

The spring mechanism may include a leaf spring configured to be disposed within the channel formed in the keeper plate, with one end of the leaf spring being attached to an end of the indicator rod and the other end of the leaf spring having a mounting portion which is adapted for attachment between the keeper plate and the door on which it is mounted. The indicator rod passes through an opening provided in the door and the spring is operative to maintain this indicator in its recessed position when the chain is not installed. When, however, the fastening member of the chain is inserted within the enlarged portion formed in the keeper plate and is slidably moved via the slot toward the opposite end of the keeper plate, the fastening member is cammed against the leaf spring and is operative to force the spring toward the surface of the door, thereby also forcing the indi cator rod outwardly of the outside surface of the door. The outward protrusion of the indicator rod provides the visual indication of the locked door. Alternatively, the spring mechanism may include a coil spring wound around the indicator rod and disposed within the keeper plate channel between the surface of the door and a camming surface located within the keeper plate channel.

It will be appreciated that the present invention provides an indicator lock mechanism which is extremely simple and which can be employed with otherwise conventional chain locks. For example, the spring mechanism may be separately fabricated and installed with the keeper plate on a door to provide operation according to the invention. The indicator mechanism could also be formed as part of the keeper plate and preassembled therewith so that a keeper plate having an indication capability can then be installed on a 'door with which it is to be employed.

DESCRIPTION OF THE DRAWINGS The invention will be more fully understood from the following detailed description, taken in conjunction with the accompanying drawings in which:

FIG. 1 is a partly broken away pictorial view of a chain lock indicator according to the invention;

FIG. 2 is a pictorial view of a chain lock indicator according to the invention, in its unlocked condition;

FIG. 3 is a pictorial view of a chain lock indicator according to the invention, in its locked condition;

FIGS. 4 and 5 are top and side views, respectively, of an indicator mechanism according to the invention; and

FIG. 6 is an end view of an alternative embodiment of a chain lock indicator according to the invention.

DETAILED DESCRIPTION OF THE INVENTION Referring to FIG. 1, there is shown a chain lock indicator embodying the invention which includes a keeper plate 10 mounted near the opening end of a door 12, and a link chain 14 having one end connected to a mounting plate 16 which is secured to a door jamb or other surface adjacent the door 12, and the other end attached to a fastening member 18 which is adapted to be retained within keeper plate 10. Keeper plate 10 includes a generally rectangular housing 20 with first and second flanges 22 and 24 formed along the length thereof on respective opposite sides, these flanges having holes provided therein for mounting to door 12 by screws or other suitable fasteners. A rectangular channel 26 is formed along the length of housing 20 confronting the surface of door 12 to which the keeper plate is mounted. An elongated slot 28 is formed within the outer surface of housing 20 and communicating with channel 26, the position of the slot away from the opening end of door 12 having an enlarged circular opening 30' formed therein.

Mounting plate 16 is secured to the door jamb by screws or other suitable fasteners and may have a generally semicircular lip 32 formed on the top edge thereof and extending outwardly from the plane of the door jamb to accommodate fastening member 18 which may be hung onto this lip portion to neatly store the link chain 14 when not in use.

Fastening member 18 includes a cylindrical pin 34 to which are welded or otherwise attached first and second cylindrical plates 36 and 38 which are secured to cylinder 34 on either side of a link 14a to secure this link to the fastening member. A third cylindrical plate 40 is attached to one end of cylinder 34 and is dimensioned to fit within enlarged opening 30 in keeper plate 10 and to slidably move within channel 26. Cylinder 34 is of a diameter to allow slidable movement of the fastening member within slot 28, while the end plate 40 disposed within channel 26 is operative to prevent removal of the fastening member from the keeper plate other than through the enlarged opening 30'.

The indicator and spring assembly are illustrated most clearly in FIGS. 4 and 5 and include a cylindrical indicator rod 42 attached at one end and upstanding from one end of a rectangular leaf spring 44. The opposite end of leaf spring 44 is attached to or formed integrally with a rectangular mounting plate 46' disposed transversely of leaf spring 44. The leaf spring is configured to allow movement of indicator rod 42 axially thereof and, in the absence of an external force to urge indicator rod 42 into a recessed position, as will be explained hereinbelow. Leaf spring 44 is dimensioned and configured to be disposed within channel 26 of keeper plate 10, with mounting plate 46 being attached between the keeper plate and the door in a position confronting enlarged opening 30. For example, the particular mounting plate 46 illustrated herein is adapted to be secured to the keeper plate and the door by the same screws employed to fasten the inner end of the keeper plate to the door. Indicator rod 42 passes through an opening provided in door 12 and this rod is dimensioned to be somewhat greater than the thickness of door 12 so that the rod in its protruded position extends beyond the outside surface of door 12.

The operation of the novel indicator lock is illustrated in FIGS. 2 and 3 which depict, respectively, the unlocked condition and the locked condition of the lock assembly. Referring to FIG. 2, his seen that leaf spring 44 is in its normally retracted position furthest from the mounting surface of door 12, thereby urging indicator rod 42 to which leaf spring 44 is attached, into its recessed position within channel 26. The end of indicator rod 42 exposed to the outside surface of door 12 is substantially flush with this outside surface or slightly recessed within the outer surface of door 12, thereby indicating that the door chain is not in place and the door is therefore capable of being opened. An annular escutcheon plate 48 is shown in dotted outline in FIGS. 2 and 3 in the outside surface of door 12 and disposed around the end of indicator rod 42 to act as a slidable guide for the indicator rod and to provide a finished appearance to the indicator. To engage the lock and to operate the indicator mechanism, the end plate of fastening member 18 is inserted within enlarged opening 30 of keeper plate 10 and is slidably moved within channel 26 toward the opening end of door 12. Plate 40 cams with the outwardly sprung leaf spring 44 to urge this leaf spring into a flattened condition toward the mounting surface of door 12, thereby also urging indicator rod 42 outwardly of the door. As indicated in FIG. 3, the indicator rod 42 in the locked condition protrudes beyond the outer surface of door 12 to denote the engagement of the chain lock in the keeper plate.

An alternative embodiment of the invention is illustrated in FIG. 6 wherein the indicator rod 50 is formed with an annular head 52 on one end thereof, with a coil spring 54 disposed around the end of rod 50 between the mounting surface of door 12 and head 52. A thin leaf member 56, similar to leaf spring 44, is disposed within channel 26 to provide a camming surface for cooperation with plate 40 of fastening member 18. In this embodiment, indicator rod 50 is maintained in its recessed position when the lock is disengaged by the urging of coil spring 54. In the locked condition, the camming action of plate 40 on leaf member 56 forces rod 50 into its protruding position against the urging of coil spring 54 thereby to provide the intended visual indication on the outside of the door.

Various modifications and alternative implementations of the invention will now occur to those versed in the art. For example, implementation of the indicator rod and spring assembly may vary in detail, as may details of the fastening member and keeper plate.

What is claimed is:

1. A chain lock indicator comprising:

a link chain attached at one end to a fastening member and at the other end to a mounting plate adapted for attachment to a surface adjacent a movable door;

a keeper plate having an elongated slot therein configured to receive said fastening member inserted therein and to retain said member in said slot, said keeper plate being adapted for mounting on a surface of a door;

an indicator rod having a length greater by a predetermined amount than the thickness of a door with which it is employed and adapted for slidable passage through an opening in such door so that a first end of said indicator rod can selectively protrude beyond the outside surface of said door opposite the surface on which said keeper plate is mounted, and having a second end confronting said keeper plate;

means disposed within said keeper plate and operative in the absence of said fastening member in said slot to urge said indicator rod into a retracted position and operative in the presence of said fastening member in said slot to urge said indicator rod into a position protruding beyond said outside surface thereby to indicate the locked condition of said door,

2. A chain lock indicator according to claim 1 where- 1n:

said keeper plate has an elongated channel formed therein and said elongated slot is colinear with said channel and communicates therewith, said slot having an enlarged portion formed on one end thereof;

the second end of said indicator rod is slidable into a region of said channel removed from said enlarged portion; and

said fastening member includes an element configured to pass through said enlarged portion into said channel and to be retained therein by said slot, said element being adapted to cam with said means thereby to urge said indicator rod into a protruded position as said element is moved in said slot away from said enlarged portion.

3. A chain lock indicator according to claim 2 wherein said means includes a leaf spring member disposed within said channel and having one end attached to an end of said indicator rod and the other end attached to said keeper plate,

4. A chain lock indicator according to claim 2 wherein said means includes a leaf spring member disposed within said channel and having one end operatively associated with said second end of said indicator rod, and having an opposite end adapted to be secured to said keeper plate.

5. A chain lock indicator according to claim 4 wherein said leaf spring member is of T-shaped configuration, having one element of said spring member disposed within and substantially coextensive with said channel, and having a transverse element adapted for attachment between said keeper plate and said door in a position confronting the enlarged portion of said slot, said one element being movable within said channel in a plane orthogonal to the plane of said door.

References Cited UNITED STATES PATENTS 897,749 9/1908 Krafit 70-432 X 1,799,258 4/1931 Shaw 292264 3,275,364 9/1966 Quinn 292264 RICHARD E. MOORE, Primary Examiner E. I. MCCARTHY, Assistant Examiner US. Cl. X.R, 70- 2 

